The present invention relates generally to measuring fluid flow and, more particularly, to a method and apparatus for metering and controlling fluid flowing through a fluid delivery system.
A wide variety of fluid flow measuring devices have been developed for use in fluid delivery systems in an attempt to accurately determine the volume of the fluid delivered through the delivery system and, more particularly, to the volume of fluid delivered to a particular user of the fluid delivery system. Most natural gas utilities, for example, provide a gas meter at each user location. Such conventional gas meters typically include a diaphragm-type flow sensing apparatus having an accuracy that varies widely as the function of the relative pressure drop across the diaphragm and a number of environmental conditions, such as ambient temperature and relative atmospheric pressure. Such conventional gas meters are typically expensive, bulky, and very difficult to repair and maintain. Moreover, conventional gas and water utility meters require periodic manual reading of the meter in order to determine consumer usage of the fluid over a particular period of time. The manually collected fluid meter information must then be input to a computerized billing system which subsequently issues a bill to the consuming user on a periodic basis.
There is a trend in gas and water utilities towards increased competition for consumer business. Multi-tiered pricing schemes, for example, are currently being used by some utilities to charge users varying rates for gas and water depending on a particular usage. In accordance with such a pricing scheme, essential uses of natural gas, such as for air and water heating, for example, are generally priced at a lower rate than gas used for luxury purposes, such as for heating outdoor pools. Further, it is anticipated that enhanced control over gas and water delivery systems from remote locations will be desirable for providing enhanced service and safety features. It can be appreciated that conventional fluid metering devices and systems cannot be practicably adapted to provide such enhanced functionality, which will certainly be required in a de-regulated competitive utility market.
The present invention is directed to a method and apparatus for controlling demand of a fluid using a fluid information unit connectable to one or more appliance demand control units. The method includes measuring a fluid supply pressure in a supply pipe, determining that the fluid supply pressure is lower than a predetermined threshold supply pressure, and directing a control signal from the fluid information unit to the one or more demand control units to reduce demand for the fluid.
The apparatus for controlling fluid demand includes a supply pressure sensor disposed to measure a fluid supply pressure in the supply pipe and a fluid information unit connectable to the demand control unit. The fluid information unit includes a demand pressure sensor disposed to sense a fluid demand pressure in the demand pipe, a communications channel connected to the supply pressure sensor, and a processor, coupled to the supply and demand pressure sensors and couplable to the demand control unit to transmit a control signal to reduce fluid demand in response to a measured supply pressure falling below a predetermined supply threshold level.
Another embodiment of the invention is directed to a method and apparatus for measuring density of a fluid flowing through a demand pipe. The method includes determining that fluid flow through the demand pipe is stable, measuring fluid flow rate through the demand pipe, preventing the fluid from flowing into the demand pipe for a sample period of time, measuring a drop in fluid pressure in the demand pipe during the sample period, and determining the density from the measured pressure drop.
The apparatus for measuring fluid density includes a fluid dispensing unit including a controllable valve couplable to an inlet of the demand pipe and a fluid information unit. The fluid information unit includes a demand pressure sensor for sensing a demand fluid pressure of the fluid in the demand pipe, a first communication channel between the fluid information unit and the controllable valve of the fluid dispensing unit, and a processor, coupled to the demand pressure sensor and the controllable valve, for controlling the controllable valve between a closed and an open position to regulate the fluid flowing through the controllable valve.
Another embodiment of the invention is directed to a utility meter for metering a fluid flowing through a supply pipe and a demand pipe. The meter includes a metering unit connectable between the supply pipe and the demand pipe to measure fluid flow therebetween, a control unit, coupled to the metering unit, to receive metering information therefrom; and an audible indicator connected to the control unit, to provide an audible signal to a user.